The Making of Species 



if the varying" individual did not actually trans- 

 mit to its offspring its newly acquired char- 

 acter, it would undoubtedly transmit to them, as 

 long as the existing conditions remained the 

 same, a still stronger tendency to vary in the 

 same manner. There can also be little doubt 

 that the tendency to vary in the same manner 

 has often been so strong that all the individuals 

 of the same species have been similarly modified 

 without the aid of any form of selection. Or 

 only a third, fifth, or tenth part of the indi- 

 viduals may have been thus affected, of which 

 fact several instances could be given. Thus 

 Graba estimates that about one-fifth of the 

 guillemots in the Faroe islands consist of a 

 variety so well marked, that it was formerly 

 ranked as a distinct species under the name 

 Uria lacrymans. In cases of this kind, if the 

 variation were of a beneficial nature, the original 

 form would soon be supplanted by the modified 

 form, through the survival of the fittest." Here 

 we seem to have a plain statement of the origin 

 of new forms by mutation. 



Again, we read (page 34) : " Some variations 

 useful to him (i.e. man) have probably arisen 

 suddenly, or by one step ; many botanists, for 

 instance, believe that the fuller's teasel, with its 

 hooks, which cannot be rivalled by any mechanical 

 contrivance, is only a variety of the wild Dipsacus ; 

 and this amount of change may have suddenly 



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